The present invention is related to foam rubber insoles which contain an antimicrobial agent to inhibit the growth of bacteria and fungi so as to aid in the prevention and treatment of microbial infections such as athlete's foot. The insoles typically further contain a deodorizing agent.
When feet are enclosed in shoes, sneakers, etc., they have a tendency to perspire. This warm, moist condition is ideal in promoting the prolific growth of bacteria and fungi. The organisms can produce an unpleasant, undesirable odor during proliferation and also can cause infections of the foot leading to the common condition known as athlete's foot. The regular application of an antimicrobial and antifungal agent to the infected area will cure or alleviate the infection, but compliance with a regimen of topical applications is difficult and, furthermore, the use of powders, creams and/or lotions causes soiling of footwear such as socks and shoes. A clean, dry, and long-acting source of the antimicrobial agent in contact with the source of infection is very desirable.
Initial attempts to use an antimicrobial agent such as parachlorometaxylenol (PCMX) were unsuccessful due to the volatility of the compound, which resulted in its loss during manufacture of the insole as a result of the heat treatment required for curing of the preparation. A solution to this problem is achieved by the present invention by using Ottacide-P (trademark of Ottawa Chemical Division of Ferro Corporation), a stable, non-volatile borate ester of PCMX having the formula: ##STR1## Ottacide-P is only partially lost during the manufacture of the insole and as such it retains its antimicrobial activity.
It has been reported that Ottacide-P is useful fungicide when incorporated in plastics. Ritzinger, Rubber & Plastics Age 40, 1067 (1959), indicates that Ottacide-P is a useful fungicide when compounded with neoprene. The product brochure of Ottawa Chemical Division of Ferro Corporation for Ottacide-P and Chemical Engineering News, Jan. 26, 1959, p. 49, indicate that Ottacide-P inhibits fungus growth on polyvinylchloride and its copolymers when incorporated therein. None of these references describes the concept of the present invention wherein the impregnated foam rubber acts as a source of antifungal agent to protect the user from infection and to aid in treatment of infection if contacted before use of the impregnated insoles.